TH350 Adjustable Transmission Crossmember for Chevy C10

This is an adjustable tubular transmission crossmember for 1963-1987 Chevrolet and GMC C10 and C20 two-wheel-drive trucks, including Blazer and Suburban, and it replaces Classic Performance style part number CP-1108G. It is built from 2-inch bent steel tubing with 1/4-inch mounting plates and a black anti-rust finish, and it ships with the rear transmission mount and mounting hardware. It uses the standard GM-type rubber mount, so nothing exotic is needed to finish the job.

The reason it exists is transmission swaps. The factory crossmember on these trucks was located for a Powerglide or a TH350, and the moment you move to a longer case the original mounting point is in the wrong place. This one slides fore and aft so the mount lands where the new case wants it, and the pad pattern accepts TH350, TH400, 700R4, 4L60, 4L60E, 4L65E, 4L70E, 4L75E, 4L80E, 6L80 and 6L90. That covers the common upgrade paths on a C10: TH350 to 700R4 or 4L60E for an overdrive gear, or a 4L80E or 6L80 behind an LS.

On the bench it is a bolt-in in most trucks. Support the tail of the transmission on a jack, unbolt the old crossmember, set this one in using the existing frame holes, then slide the crossmember until the mount studs line up with the tailhousing pad before you torque anything. Set driveline angle with the jack first, then snug the frame bolts. It can also be welded in if the frame has been boxed or the holes are wallowed out. The tubing is bent to clear long tube headers and exhaust up to 4 inches, and it sits above the frame rails so a lowered truck does not drag it on the pavement.

Check your frame rail spacing and the length of the case you are installing before ordering. This is the 2WD truck crossmember only; 4x4 C/K trucks use a different rear mount location and it will not adapt.